On Sun, Aug 19, 2018 at 11:37:59PM +0200, Andrei Rybak wrote:
> On 19/08/18 22:32, Jeff King wrote:
> > On Sun, Aug 19, 2018 at 07:50:42PM +0200, Andrei Rybak wrote:
> >
> >> 1. Check both files at the same time (combination with Gábor's
> >> function):
> >>
> >> test_cmp () {
> >> if test "$1" != - &&
> >> test "$2" != - &&
> >> ! test -s "$1" &&
> >> ! test -s "$2"
> >> then
> >> error "bug in test script: using test_cmp to check empty file; use test_must_be_empty instead"
> >> fi
> >> test_cmp_allow_empty "$@"
> >> }
> >>
> >> This will still be reporting to the developer clearly, but
> >> will only catch cases exactly like the bogus test in t5310.
> >
> > Doesn't that have the opposite issue? If we expect non-empty output but
> > the command produces empty output, we'd say "bug in the test script".
> > But that is not true at all; it's a failed test.
>
> No. Only when both "$1" and "$2" are empty files will the function above
> report "bug in test script". From patch's commit message:
Oh, you're right. Somewhere between the screen and my brain the "&&"
became an "||".
I agree that works, and has the advantage that the arguments are treated
symmetrically. We _might_ say "test failure" instead of "bug in test"
when the expectation is empty and the generated output is not (because
we do not know which is which), but I think that would be uncommon (and
the most important thing is that we do not silently consider it a pass).
> > If we assume that "expect" is first (which is our convention but not
> > necessarily guaranteed), then I think the best logic is something like:
> >
> > if $1 is empty; then
> > bug in the test script
> > elif test_cmp_allow_empty "$@"
> > test failure
> >
> > We do not need to check $2 at all. An empty one is either irrelevant (if
> > the expectation is empty), or a test failure (because it would not match
> > the non-empty $1).
>
> ... this is indeed a better solution. I written out the cases for
> updated test_cmp to straighten out my thinking:
I'd be OK pursuing either this line, or what you showed originally.
-Peff
